This project uses different systems to develop objective and subjective methods to monitor and document opacities in the human lens. We are actively recruiting patients with and without cataracts for reproducibility studies on the objective systems~the Scheimpflug (Zeiss and Oxford) and retroillumination (Neitz and Oxford) cameras. Our study of subjective systems or methods such as the LOCS II grading system and the effects of cataracts on visual perception, contrast sensitivity, and glare may be useful in identifying additional parameters for monitoring cataract presence, progression, or regression. We are now using these systems to study the natural history of various cataracts, such as presenile, senile, or age-related, steroid-induced, radiation, diabetic, retinitis pigmentosa, gyrate atrophy, and neurofibromatosis 2 cataracts. This study will prepare the way for eventual clinical trials of anticataract drugs. Genetic linkage studies now under way are pursuing the gene(s) of congenital cataract.